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Wednesday, June 15, 2011

Learning to Live with Your Powerstroke 6.0L EGR

One look at the picture below explains why I am not a fan of EGR systems, especially on the Powerstroke. However, ever-stricter emissions regulations pushed Ford to adopt them on its diesels, but judging by how much warranty money Ford has unloaded on failed EGR coolers, I'm guessing that the coolers are not on its list of top ten company moneymakers. The early 6.0 L Power Stroke engines have proven themselves to be unreliable. Folks have speculated that they cost Ford hundreds of millions of dollars in warranty repairs. The 2003 through early 2005 models led to many recalls and the repurchase of at least 500 trucks. I can’t find exact figures on how many EGR coolers have failed from those model years, but I would guess it in the high hundreds of thousands. Ford sold several hundred thousand 6.0Ls a year for five years both in E-series and F-series flavors. Quality improved drastically by 2006, but if your one of the luckyones who owns one of the earlier 6.0L Powerstroke there's a good chance you know, first hand, what I am talking about. Let’s take a look at the Powerstroke EGR system, what you can expect and how you might make the best of a bad situation.

The EGR System on the Powerstroke

Exhaust gas recirculation systems take gases from the exhaust and re-introduce them into the combustion process in order to lower temperatures. Since the exhaust gases have already run through the combustion process, they are inert and actually serve to retard combustion. The result is lower temperatures which means a decrease in the oxides of nitrogen (NOx) produced by the engine and introduced into the atmosphere. You have probably already been made aware that NOx are a component in the formation of smog and acid rain which is why the government wants to keep them as low as they can.

The Ford Powerstroke uses an EGR cooler and valve to send exhaust gases into the intake manifold where they enter the combustion process. The EGR cooler used in the 6.0L Powerstroke varies by model year. The 2003 and early 2004 engines used a shorter length, round cooler. If you remove it from the engine and look down the cooler you will see it has tubes running the length of the cooler assembly. This was a very solid cooler that has caused little trouble.

The original Powerstroke EGR Cooler (2003 to early 2004) looks similar to the aftermarket cooler on the left. The newer, less reliable EGR coolers contain fins similar to a radiator and a prone to leaking coolant into the exhaust system.

In the earlier configuration, the exhaust pipe runs from the exhaust manifold to the turbo with a smaller pipe teeing out to connect to the EGR cooler. Late build 2004 and newer 6.0L Powerstrokes use a longer and more squareish cooler. If you look down this later build cooler off the vehicle, you will notice it has fins like a radiator. Of course with the two different length coolers the pipe teeing off of the exhaust pipe is also different lengths and they are not interchangeable.

Powerstroke 6.0L EGR Diagram

Unfortunately, the late 2004 and after cooler model is the source of a lot of headaches. The main problem is that it blows out a lot. When this occurs, the unit sends coolant into the exhaust system, causing white smoke and steam. It can also push coolant out of the degas bottle cap when exhaust pressure gets into the cooling system, causing the cap to vent coolant out.

Coolant venting from a Powerstroke degas cap as the result of exhaust pressure ultimately caused by an EGR blowout.

The problems only get worse from there. An EGR blowout can also cause the engine to hydraulically lock when coolant from a blown EGR enters the combustion chambers through the intake valves. When an EGR blowout is severe enough, it can have the exact same symptoms as a blown head gasket. In fact, I believe a lot of head gaskets were replaced due to bad EGR coolers throwing technicians off; this occurred more frequently when the new EGR coolers were first introduced in mid 2004 and Ford techs were lacking the training they needed to properly diagnose the issue. While it is absolutely true that the head gaskets on the 6.0L do blow out much more than is acceptable in my opinion – a topic I'll look forward to covering in a separate article – the EGR system has also often been the source of engine problems. Fortunately, the training caught up with the issue and technicians, in general, are much better prepared to catch the EGR as the source of the problem.

From what I have observed, the Powerstoke's EGR woes started with less-than-stellar 6.0L research and development by Ford. Ford, however, laid the blame on owners’ failure to properly maintain their trucks with timely oil changes. Ford claimed that this resulted in the oil cooler clogging up, building excessive up pressure and then blowing out the EGR cooler. While I will admit that too many of us aren't as careful as we should be about sticking with recommended oil changes – or using an oil that will allow us to extend oil drain intervals – I certainly do not think that all, or even most, of the EGRs problems can be blamed on the customers (and don't we love it when they blame us for the problem). While failure to service your oil properly can lead to multiple issues with the 6.0L Powerstroke (I recommend staying on top of this), I have also seen clogged oil coolers cause blown EGR coolers on engines that have had their oil changed every 5,000 miles. To make my case that Ford failed to produce and implement a quality EGR system, I will simply point out that on the 6.4L Powerstroke Ford designed the EGR and oil cooler systems so that the EGR cooler is unaffected if the oil cooler clogs.

Soot and EGR Valve Maintenance

While the design flaw discussed above is the result of the interior components of the later model 6.0 Powerstroke EGR coolers, the EGR valve itself has proven itself to be reliable. This electric motor valve is basically the same one used in GM gasoline engines and is operated by the PCM. The valve does have some trouble with soot buildup however. Given that the use of any EGR in diesel engines creates a soot rich environment, we have to learn to mitigate the problems it causes.

The valve on the left is relatively clean because it is from a truck with a failed EGR cooler (the coolant from the blown EGR cooler removed the soot). The soot-covered valve on the right is typical of an EGR valve that is part of a working EGR system on the Powerstroke 6.0L.

Ford recommends running cetane booster in your fuel and that does seem to help some. Actually, I would recommend running cetane boost regularly because it helps with more than just soot build up: since it is basically impossible to get quality diesel fuel from fuel stations nowadays and because diesel is known for water build up anyway, cetane boost in your diesel fuel can avoid a multitude of issues. Cetane boost reduces idle timing in an EGR-equipped diesel and also keeps the water in your fuel in suspension so that it will be less likely to take out expensive fuel injectors. If you store your truck, cetane boost is very important.

The EGR valve can be checked for proper operation with the Ford IDS diagnostic tool. If you do not have one of these, you can pull it out and inspect it if you have reason to suspect it is causing troubles such as a loss of power or vehicle smoking / surging. Once you have the EGR valve removed, you should look for both the amount of soot build up and the kind of soot build up. Dry, dusty soot is usually a sign of normal EGR operation and not a threat to the engine. It can, however, get thick and may eventually get thick enough to cause the valve to hang open (sometimes this will not register on a scan). While this may seem a design flaw, it is really part of living with the high soot and will, sooner or later, have to be dealt with. I have sometimes gotten away with cleaning dust-covered EGR valves really well with some carb or brake cleaner. It is certainly worth a try, since replacing an EGR valve at our shop will set you back over $300.

A clogged Powerstroke 6.0L EGR valve can set you back over $300. The good news? You may be able to clean it yourself and keep the cash.

While dry soot is part of the normal operation of the EGR system, wet soot is another story. If you have an EGR valve is covered with wet soot, it means that there will be wet soot down in the intake as well. This is an indication of some type of engine concern. It could be motor oil, or a mixture of motor oil and fuel resulting from a stuck open fuel injector/injectors that are overfilling the crankcase and causing oil to get sucked up into the intake. If the engine oil is at the normal level, it could also be a sign of a EGR cooler that is beginning to leak. (Another possibility may be an internal turbo issue that is allowing motor oil to leak past its seals into the intake. If this is the case, you can get a Center Housing Rotating Assembly from a Ford dealer and rebuild your 6.0L turbo which will save some money over buying a new turbo. This will work if you have above average do-it-yourself mechanical skills. I will warn you that the exhaust clamps on the back of the turbo can sometimes be a bear – arm yourself with some patience before you get started.)

A final note: the 2003 to mid-2004 6.0L Powerstrokes use an EGR Throttle plate. Visual inspection is the only way to see if this is the case on your truck. It will be on the charge air cooler inlet cold side of the intake (the other charge air cooler hose is coming off of the turbo). It operates like any electronic throttle with a 12-volt electric motor that moves the plate and a potentiometer throttle position sensor to send feedback to the PCM. Its purpose is to lower intake manifold pressure and to allow exhaust gases to flow freely into the intake manifold in order to avoid pressure pushing the EGR gases back the wrong way.

To be fair to Ford, it appears to have learned from its mistakes. Many changes were made in 2005 and by 2006 the reliability of the 6.0L Powerstrokes has been excellent. In fact, the 2006 model year 6.0L engines had the lowest rate of warranty claims across the board for Ford Motor Company for not only its diesel engines but its gas engines as well.